procurement-ingest/cdk/wo_stack.py

"""CDK stack for the work order email ingestion pipeline."""

import aws_cdk as cdk
from aws_cdk import (
    Duration,
    RemovalPolicy,
    Stack,
    aws_cloudwatch as cloudwatch,
    aws_cloudwatch_actions as cw_actions,
    aws_dynamodb as dynamodb,
    aws_lambda as lambda_,
    aws_logs as logs,
    aws_s3 as s3,
    aws_s3_notifications as s3n,
    aws_ses as ses,
    aws_ses_actions as ses_actions,
    aws_secretsmanager as secretsmanager,
    aws_sns as sns,
    aws_sqs as sqs,
)
from constructs import Construct

# Operations these tables actually issue (PutItem/UpdateItem/DeleteItem writes,
# GetItem/Query/BatchGetItem reads). DynamoDB emits ThrottledRequests/SystemErrors
# keyed by TableName + Operation only, so the CDK *_for_operations helpers (which
# render a SUM MathExpression across these per-operation metrics) are the correct,
# non-deprecated way to roll a table up to a single alarmable series.
_DDB_ALARM_OPERATIONS = [
    dynamodb.Operation.GET_ITEM,
    dynamodb.Operation.BATCH_GET_ITEM,
    dynamodb.Operation.QUERY,
    dynamodb.Operation.SCAN,
    dynamodb.Operation.PUT_ITEM,
    dynamodb.Operation.UPDATE_ITEM,
    dynamodb.Operation.DELETE_ITEM,
    dynamodb.Operation.BATCH_WRITE_ITEM,
]


def _add_ddb_alarms(scope, id_prefix, table, alarm_name_prefix, alarm_topic):
    """Add throttle + system-error alarms for a DynamoDB table.

    Both fire on any non-zero datapoint in a 5-min window. ALARM-only SnsAction
    to site-alerts (no OK action); TreatMissingData NOT_BREACHING.
    """
    table.metric_throttled_requests_for_operations(
        operations=_DDB_ALARM_OPERATIONS,
        period=Duration.minutes(5),
        statistic="Sum",
    ).create_alarm(
        scope,
        f"{id_prefix}ThrottlesAlarm",
        alarm_name=f"{alarm_name_prefix}-throttles",
        alarm_description=f"{alarm_name_prefix} DynamoDB throttled requests",
        threshold=0,
        evaluation_periods=1,
        comparison_operator=cloudwatch.ComparisonOperator.GREATER_THAN_THRESHOLD,
        treat_missing_data=cloudwatch.TreatMissingData.NOT_BREACHING,
    ).add_alarm_action(cw_actions.SnsAction(alarm_topic))

    table.metric_system_errors_for_operations(
        operations=_DDB_ALARM_OPERATIONS,
        period=Duration.minutes(5),
        statistic="Sum",
    ).create_alarm(
        scope,
        f"{id_prefix}SystemErrorsAlarm",
        alarm_name=f"{alarm_name_prefix}-system-errors",
        alarm_description=f"{alarm_name_prefix} DynamoDB server-side (5xx) errors",
        threshold=0,
        evaluation_periods=1,
        comparison_operator=cloudwatch.ComparisonOperator.GREATER_THAN_THRESHOLD,
        treat_missing_data=cloudwatch.TreatMissingData.NOT_BREACHING,
    ).add_alarm_action(cw_actions.SnsAction(alarm_topic))


# CloudWatch namespace for the log-derived sender-authentication metrics.
_SENDER_AUTH_METRIC_NAMESPACE = "Seahaven/ProcurementIngest"


def _add_sender_auth_rejected_alarm(scope, id_prefix, function_name, alarm_topic):
    """Metric-filter + alarm on ``sender_auth_rejected`` warnings (INFRA-107).

    A rejected inbound email is skipped without erroring the invocation, so it
    is invisible to the Errors/Throttles/DLQ alarms. This turns the structured
    warning log into a CloudWatch metric and pages when rejections spike --
    catching a silent false-reject storm (allowlist wrong, signing-domain
    drift, SES header-format change) that would otherwise discard legitimate
    mail while the pipeline reports healthy. This is the safety net for the WO
    allowlist domain assumption (seahaven.com) -- if the real Gmail-forward
    re-signing domain differs, this alarm surfaces it instead of a silent
    work-order outage.

    ALARM-only SnsAction to site-alerts; no OK action. The metric filter reads
    the function's own log group (imported by the deterministic
    ``/aws/lambda/<fn>`` name, created by the function's log_retention). A plain
    substring pattern is used because Lambda prefixes each line with its own
    level/timestamp/request-id, so the JSON payload is not a standalone JSON
    log event a `{$.event=...}` pattern could match.
    """
    metric_name = f"{function_name}-sender-auth-rejected"
    logs.MetricFilter(
        scope,
        f"{id_prefix}SenderAuthRejectedFilter",
        log_group=logs.LogGroup.from_log_group_name(
            scope,
            f"{id_prefix}LogGroup",
            f"/aws/lambda/{function_name}",
        ),
        filter_pattern=logs.FilterPattern.literal('"sender_auth_rejected"'),
        metric_namespace=_SENDER_AUTH_METRIC_NAMESPACE,
        metric_name=metric_name,
        metric_value="1",
        default_value=0,
    )

    # Fire on a *sustained* reject condition rather than a volume spike. The
    # earlier Sum>=3-over-15-min threshold had a blind spot that is exactly the
    # failure this alarm exists to catch: a low-traffic pipeline in total
    # drift outage (allowlist wrong / signing-domain changed) may only produce
    # a trickle of rejects -- one every few minutes -- that never sums to 3 in
    # any window, so the outage never pages. Instead: >=1 reject per 5-min
    # period, alarming when 2 of the last 3 periods breach (evaluation_periods=3
    # / datapoints_to_alarm=2, the same idiom as the duration alarm). A single
    # stray spoof probe (one lone period) is tolerated and self-clears, but a
    # sustained reject condition trips within ~10-15 min even at one reject per
    # period. default_value=0 on the metric filter keeps the series continuous
    # so NOT_BREACHING only applies before the first datapoint ever arrives.
    cloudwatch.Metric(
        namespace=_SENDER_AUTH_METRIC_NAMESPACE,
        metric_name=metric_name,
        period=Duration.minutes(5),
        statistic="Sum",
    ).create_alarm(
        scope,
        f"{id_prefix}SenderAuthRejectedAlarm",
        alarm_name=f"{function_name}-sender-auth-rejected",
        alarm_description=(
            f"{function_name} rejected inbound mail on sender authentication "
            "(possible allowlist/DKIM-domain drift silently dropping real mail)"
        ),
        threshold=1,
        evaluation_periods=3,
        datapoints_to_alarm=2,
        comparison_operator=cloudwatch.ComparisonOperator.GREATER_THAN_OR_EQUAL_TO_THRESHOLD,
        treat_missing_data=cloudwatch.TreatMissingData.NOT_BREACHING,
    ).add_alarm_action(cw_actions.SnsAction(alarm_topic))


class WorkorderIngestStack(Stack):
    def __init__(self, scope: Construct, construct_id: str, **kwargs):
        super().__init__(scope, construct_id, **kwargs)

        # --- Shared alarm SNS topic (site-alerts) ---
        # Imported once near the top so every alarm in this stack reuses the same
        # Topic construct instance (avoids duplicate logical IDs). ALARM-only
        # SnsAction; no OK action, per the CloudWatch-alarm preference. The
        # topic's CMK (alias/seahaven-alarm-topics) lives on the topic itself.
        alarm_topic = sns.Topic.from_topic_arn(
            self,
            "SiteAlertsTopic",
            f"arn:aws:sns:{self.region}:{self.account}:site-alerts",
        )

        # --- S3 bucket for raw emails ---
        email_bucket = s3.Bucket(
            self,
            "EmailBucket",
            bucket_name=f"workorder-ingest-emails-{self.account}",
            block_public_access=s3.BlockPublicAccess.BLOCK_ALL,
            removal_policy=RemovalPolicy.RETAIN,
            lifecycle_rules=[
                s3.LifecycleRule(expiration=Duration.days(90)),
            ],
        )

        # --- DynamoDB tables ---
        work_orders_table = dynamodb.Table(
            self,
            "WorkOrdersTable",
            table_name="WorkOrders",
            partition_key=dynamodb.Attribute(
                name="work_order_id",
                type=dynamodb.AttributeType.STRING,
            ),
            billing_mode=dynamodb.BillingMode.PAY_PER_REQUEST,
            removal_policy=RemovalPolicy.RETAIN,
        )
        # site-code-index and status-index GSIs removed 2026-06-03 (audit M-20):
        # 0 reads in 30d against ~50k WCU each of write amplification. Re-add if
        # a site-code or status query path ships.

        comments_table = dynamodb.Table(
            self,
            "CommentsTable",
            table_name="WorkOrderComments",
            partition_key=dynamodb.Attribute(
                name="work_order_id",
                type=dynamodb.AttributeType.STRING,
            ),
            sort_key=dynamodb.Attribute(
                name="comment_id",
                type=dynamodb.AttributeType.STRING,
            ),
            billing_mode=dynamodb.BillingMode.PAY_PER_REQUEST,
            removal_policy=RemovalPolicy.RETAIN,
        )

        # --- Secrets Manager for Anthropic API key ---
        anthropic_secret = secretsmanager.Secret(
            self,
            "AnthropicApiKey",
            secret_name="workorder-ingest/anthropic-api-key",
            description="Anthropic API key for work order email parsing",
            removal_policy=RemovalPolicy.RETAIN,
        )

        # --- DLQ for failed async invocations (INFRA-41 / audit H-8) ---
        # SES → S3 → Lambda is async; without an OnFailure destination a failed
        # parse (bad email, transient error) is silently dropped after Lambda's
        # retries. CDK generates the queue name to avoid colliding with the
        # interim CLI-created workorder-email-processor-dlq (removed post-deploy).
        email_processor_dlq = sqs.Queue(
            self,
            "EmailProcessorDlq",
            retention_period=Duration.days(14),
            enforce_ssl=True,
        )

        # --- Lambda function ---
        email_processor = lambda_.Function(
            self,
            "EmailProcessor",
            function_name="workorder-email-processor",
            runtime=lambda_.Runtime.PYTHON_3_12,
            architecture=lambda_.Architecture.ARM_64,
            handler="handler.handler",
            code=lambda_.Code.from_asset(
                "../lambdas/wo/email_processor",
                bundling=cdk.BundlingOptions(
                    image=lambda_.Runtime.PYTHON_3_12.bundling_image,
                    command=[
                        "bash",
                        "-c",
                        "pip install --platform manylinux2014_aarch64 --only-binary=:all: "
                        "-r requirements.txt -t /asset-output && "
                        "cp -r . /asset-output/",
                    ],
                ),
            ),
            timeout=Duration.seconds(60),
            memory_size=256,
            log_retention=logs.RetentionDays.TWO_MONTHS,
            dead_letter_queue=email_processor_dlq,
            environment={
                "WORK_ORDERS_TABLE": work_orders_table.table_name,
                "COMMENTS_TABLE": comments_table.table_name,
                "ANTHROPIC_API_KEY_SECRET_ARN": anthropic_secret.secret_arn,
                # Fail-closed sender auth (INFRA-107): the handler only
                # accepts mail whose SES-stamped Authentication-Results
                # header carries dkim=pass for one of these domains. APM
                # mail arrives via the apm@ Google Groups forward, which
                # re-signs as seahaven.com (observed on live traffic
                # 2026-07-15: "dkim=pass header.i=@seahaven.com"; the
                # original hxgnsmartcloud.com signature does not survive
                # the forward). Unset/empty ⇒ the handler rejects all mail.
                "ALLOWED_DKIM_DOMAINS": "seahaven.com",
            },
        )

        # Grant permissions
        email_bucket.grant_read(email_processor)
        work_orders_table.grant_read_write_data(email_processor)
        comments_table.grant_read_write_data(email_processor)
        anthropic_secret.grant_read(email_processor)

        # NOTE: The pre-emptive grant_encrypt_decrypt on the shared DynamoDB CMK
        # (alias/seahaven-dynamodb) was removed (security sweep 2026-06-17). The
        # WorkOrders/WorkOrderComments tables are NOT SSE-KMS encrypted with that
        # CMK, so the grant was unused for these tables yet handed
        # wo-email-processor kms:Decrypt on the CMK that also protects the
        # purchase-orders table (cross-stack decrypt reach). Re-add this grant only
        # as part of the actual CMK migration of these tables (INFRA-6), at which
        # point grant_read_write_data on the (then encrypted) tables would propagate
        # the needed key permissions automatically.

        # --- Errors alarm (INFRA-41 / audit H-8) ---
        # ALARM-only (no OK action, per the CloudWatch-alarm preference) to the
        # shared site-alerts topic. Any errored invocation in a 5-min window pages.
        email_processor.metric_errors(
            period=Duration.minutes(5),
            statistic="Sum",
        ).create_alarm(
            self,
            "EmailProcessorErrorsAlarm",
            alarm_name="workorder-email-processor-errors",
            alarm_description="workorder-email-processor async invocation errors",
            threshold=0,
            evaluation_periods=1,
            comparison_operator=cloudwatch.ComparisonOperator.GREATER_THAN_THRESHOLD,
            treat_missing_data=cloudwatch.TreatMissingData.NOT_BREACHING,
        ).add_alarm_action(cw_actions.SnsAction(alarm_topic))

        # --- Sender-auth rejection alarm (INFRA-107) ---
        # A rejected email (bad/unaligned DKIM verdict) returns normally, so it
        # produces NO Lambda error, NO DLQ message and NO retry -- only a
        # `sender_auth_rejected` warning log. The WO allowlist trusts dkim=pass
        # for seahaven.com on the assumption the apm@ forward re-signs there; if
        # that assumption is wrong (e.g. a Gmail auto-forward re-signs under a
        # different domain), 100% of legitimate work-order mail is silently
        # dropped. This metric filter + alarm turns those warnings into a paging
        # signal so a false-reject storm surfaces instead of a silent outage.
        _add_sender_auth_rejected_alarm(
            self, "EmailProcessor", "workorder-email-processor", alarm_topic
        )

        # --- Throttles alarm: workorder-email-processor ---
        # Any throttled invocation (concurrency cap hit) in a 5-min window pages.
        # ALARM-only to site-alerts; no OK action; NOT_BREACHING when no data.
        email_processor.metric_throttles(
            period=Duration.minutes(5),
            statistic="Sum",
        ).create_alarm(
            self,
            "EmailProcessorThrottlesAlarm",
            alarm_name="workorder-email-processor-throttles",
            alarm_description="workorder-email-processor invocation throttles",
            threshold=0,
            evaluation_periods=1,
            comparison_operator=cloudwatch.ComparisonOperator.GREATER_THAN_THRESHOLD,
            treat_missing_data=cloudwatch.TreatMissingData.NOT_BREACHING,
        ).add_alarm_action(cw_actions.SnsAction(alarm_topic))

        # --- Duration alarm: workorder-email-processor (orphan adoption) ---
        # Adopts the orphaned CLI alarm Lambda-Duration-workorder-email-processor
        # under the repo's <fn>-duration naming (NEW logical name → no deploy
        # collision; delete the orphan post-deploy). p95 /
        # 45000 ms (75% of the 60s timeout) / eval 3 of which 2 datapoints —
        # tighter than the orphan's Maximum>=48000 / 1-of-1.
        email_processor.metric_duration(
            period=Duration.minutes(5),
            statistic="p95",
        ).create_alarm(
            self,
            "EmailProcessorDurationAlarm",
            alarm_name="workorder-email-processor-duration",
            alarm_description="workorder-email-processor p95 duration approaching the 60s timeout",
            threshold=45000,
            evaluation_periods=3,
            datapoints_to_alarm=2,
            comparison_operator=cloudwatch.ComparisonOperator.GREATER_THAN_OR_EQUAL_TO_THRESHOLD,
            treat_missing_data=cloudwatch.TreatMissingData.NOT_BREACHING,
        ).add_alarm_action(cw_actions.SnsAction(alarm_topic))

        # --- DLQ messages-present alarm (INFRA-41 / audit H-8) ---
        # The errors alarm above fires on any errored invocation, but a message
        # only lands in the DLQ after Lambda exhausts its async retries and gives
        # up — i.e. a genuinely dropped email. ALARM-only (no OK action) to the
        # same shared site-alerts topic. MAXIMUM over a 5-min window so a single
        # visible message pages even if it is later consumed/redriven.
        email_processor_dlq.metric_approximate_number_of_messages_visible(
            period=Duration.minutes(5),
            statistic="Maximum",
        ).create_alarm(
            self,
            "EmailProcessorDlqMessagesAlarm",
            alarm_name="workorder-email-processor-dlq-messages",
            alarm_description="workorder-email-processor DLQ has visible messages (dropped emails)",
            threshold=0,
            evaluation_periods=1,
            comparison_operator=cloudwatch.ComparisonOperator.GREATER_THAN_THRESHOLD,
            treat_missing_data=cloudwatch.TreatMissingData.NOT_BREACHING,
        ).add_alarm_action(cw_actions.SnsAction(alarm_topic))

        # S3 event notification -> Lambda
        email_bucket.add_event_notification(
            s3.EventType.OBJECT_CREATED,
            s3n.LambdaDestination(email_processor),
            s3.NotificationKeyFilter(prefix="inbound/"),
        )

        # --- SES Receipt Rule ---
        rule_set = ses.ReceiptRuleSet.from_receipt_rule_set_name(
            self,
            "ExistingRuleSet",
            "INBOUND_MAIL",
        )

        rule_set.add_rule(
            "WorkorderEmailRule",
            recipients=["apm@int.seahaven.com"],
            actions=[
                ses_actions.S3(
                    bucket=email_bucket,
                    object_key_prefix="inbound/",
                ),
            ],
        )

        # --- Web UI auth token secret ---
        # Shared secret for the web UI auth gate, stored in Secrets Manager and
        # resolved at runtime so the token never appears in CloudFormation templates
        # or Lambda environment variables. Create this secret before deploying
        # either stack; both PO and WO stacks reference it by name.
        web_ui_auth_secret = secretsmanager.Secret.from_secret_name_v2(
            self,
            "WebUiAuthToken",
            "procurement-ingest/web-ui-auth-token",
        )

        # --- Web UI Lambda ---
        web_ui = lambda_.Function(
            self,
            "WebUI",
            function_name="workorder-web-ui",
            runtime=lambda_.Runtime.PYTHON_3_12,
            architecture=lambda_.Architecture.ARM_64,
            handler="handler.handler",
            code=lambda_.Code.from_asset("../lambdas/wo/web_ui"),
            timeout=Duration.seconds(15),
            memory_size=128,
            log_retention=logs.RetentionDays.TWO_MONTHS,
            environment={
                "WORK_ORDERS_TABLE": work_orders_table.table_name,
                "COMMENTS_TABLE": comments_table.table_name,
                # Defense-in-depth shared secret for the web UI handler. The
                # handler fails closed if this ARN is unset or the secret is
                # missing, so any future invocation path cannot re-expose the
                # WO DB unauthenticated. The secret value is fetched at runtime
                # from Secrets Manager (not embedded in env vars or template).
                "WEB_UI_AUTH_TOKEN_SECRET_ARN": web_ui_auth_secret.secret_arn,
            },
        )

        work_orders_table.grant_read_data(web_ui)
        comments_table.grant_read_data(web_ui)
        web_ui_auth_secret.grant_read(web_ui)

        # --- DynamoDB throttle + system-error alarms ---
        # ThrottledRequests / SystemErrors emit at TableName + Operation only
        # (verified against live CloudWatch: no TableName-only rollup exists, and
        # metric_throttled_requests is deprecated/invalid in aws-cdk-lib 2.259.0).
        # Each table currently has zero throttle/error datapoints, so the series
        # only materialise on first occurrence — NOT_BREACHING keeps them OK until
        # then.
        _add_ddb_alarms(
            self, "WorkOrdersTable", work_orders_table, "WorkOrders", alarm_topic
        )
        _add_ddb_alarms(
            self, "WorkOrderComments", comments_table, "WorkOrderComments", alarm_topic
        )

        # Public Function URL removed 2026-06-08 (INFRA-74 / audit C-5): the
        # unauthenticated FunctionUrlAuthType.NONE URL was deleted out-of-band
        # via CLI. Removing the construct (and its auto-generated Principal:*
        # invoke permission) reconciles IaC with the live state.